Variability of the currents in the Luzon Strait during spring of 2002 obtained from observations and satellite geostrophic currents and spectral analyses

Abstract

The structure and variability of the currents in the Luzon Strait during spring of 2002 are studied, based on the current measurements at the average position of the mooring station (20°49′57"N, 120°48′12"E) from March 17 to April 15, 2002, satellite geostrophic currents in the Luzon Strait, and the spectral analyses, using the maximum entropy method. The subtidal currents at the mooring station show decreased amplitudes downward with an anti-cyclonic rotation, suggesting that the currents enter and exit the South China Sea in the upper and intermediate layers, respectively. The vertical structure of the currents in the Luzon Strait suggests strongly the sandwiched structure of the LST, even though the bottom part of the profile is not resolved by the observational grid. The spectral analyses show the following periods of significant spectral peaks: (1) the tidal currents variability in the vertical direction; (2) the period about 4-6 d for the two cases of frequency f ＞0 and f＜0 at the 200 and 500 m levels, but at the 800 m level only for the case of f ＞0; (3) The fluctuation in the period range is about 2-3 days for the two cases of f ＞0 and f＜0 at the 200, 500 and 800 m levels, namely the Luzon Strait currents exhibit significant synoptical variability throughout the water column up to 800 m deep. Both direct current measurements and in situ hydrographic and satellite survey suggest no Kuroshio loop current in the Luzon Strait during the spring of 2002.

Population Genetic Structure and Gene Expression Plasticity of the Deep-Sea Vent and Seep Squat Lobster Shinkaia crosnieri

“…The Luzon Strait is the only deep channel that connects the semi-enclosed SCS with the deeper Pacific Ocean for water transportation via a sandwiched vertical structure (Tian et al, 2009). Seawater flows into the SCS from the Pacific Ocean in both the upper (<700 m) and the deep (>1,500 m) layers and exits the SCS through the Luzon Strait in the intermediate layer (700-1,500 m) (Tian et al, 2006;Yuan et al, 2009). The eastward spread is stronger in both winter and spring (You et al, 2005).…”

Seasonal Difference of the Deep Currents in the Luzon Strait during October 2008-January 2009 and July-August 2009

“…2) A period of approximately 14 d has been found with the dimensionless PSD magnitude ~12. This is the fortnightly spring-neap tidal period that has been previously reported in the LS (e.g., [1] [16]).…”

“…Overall, the exchange can be categorized into three different layers, namely, the upper layer above 400 m, the middle layer between 500 and 1200 m, and the deep layer. In the upper layer above 400 m in the LS, a considerable number of studies have discussed the westward intrusion of the Kuroshio into the SCS through the LS (e.g., [1] [2] [3] [4]). In particular, many studies have emphasized the dynamical cause of the westward Kuroshio intrusion (e.g., [2] [3] [5]- [10]).…”

Oceanic Surface Geostrophic Velocities Determined with Satellite Altimetric Crossover Method

“…Otherwise we can only get the relative geostrophic currents [7,8] . Yuan et al studied the oceanic current variability in the Luzon Strait during the spring of 2002 obtained from the practical observations at flow monitoring stations and the altimetric data provided by AVISO [9] . Zhang et al calculated the surface geostrophic currents with the grid method [10] .…”